Dental flask



DENTAL FLASK Filed July 3, 1948 2 Sheets-Sheet 1 Q FIG.3

Y INVENTOR- 77 74; @aaa ATTOR/VfY N. OPOTOW June 19, 1951 DENTAL FLASK 2 Sheets-Sheet 2 Filed July 3, 1948 FIG INVENTOR. 77m flaw BY ,2 W14. %Q

A T TO/F/VEY Patented June I 19, 1951 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to dental flasks used in dentistry for forming partial or full artificial dentures.

The present application is a continuation in part of my application Serial No. 709,566, filed November 13, 1946, issued on August 31, 1948, as Patent No. 2,448,115.

It was pointed out in the above mentioned patent application that artificial dentures are generally made by investing a lower model of the jaw structure in the lower portion of a dental flask together with the waxed up case comprising a wax model of the gums and including the teeth that appear in the finished denture. The surface of the plaster which invests the model is then coated with oil or some such separating medium and the upper section of the flask is thereafter applied over the lower section and filled with further plaster or so-called artificial stone serving as investment material. The cover is then applied and the material is allowed to set. Then, the assembled flask is immersed in boiling water for several minutes, whereupon the upper section of the flask is separated from the lower section, the wax of the waxed up case having been washed out or softened during the boiling process. A thermoplastic material, such as one of various well known acrylates or any other suitable denture material, is then applied to the space left by the molten or removed wax and the upper portion of the flask is restored. The reassembled flask is then subjected to considerable pressure in order to force the plastic material into the space left by the wax, such pressure compressing the plastic material to a high density.

As was recited in the above mentioned patent application, it has been recognized that various discrepancies between the wax pattern and the cured denture are brought about during the above process and such discrepancies account for unsatisfactory dentures.

It should further be noted that another method of investing, generally referred to as banking, has been practiced. This is accomplished by investing the teeth and model in one-half of the flask while banking the plaster around the teeth and model far above the height of the flask portion in which it is invested. The upper portion is formed with a mound of plaster which serves as a plunger. Prior to its application to the opposing denture of the flask, the wax is eliminated as above set forth and the denture is applied through the lingual sides of the waxed up case. This method assures a proper application of the plastic denture material since the upper section of the flask may be removed without risking undesirable changes in the assembly of the investment material and the model.

With the foregoing in mind, it is an object of the present invention to provide a flask which is well adapted to banking procedures, but wherein improved access to the denture is provided. This feature permits the plastic material to be applied with facility and convenience and leaves substantially no blind spots which cannot be conveniently reached by the dentist or technician.

Another object of this invention is to provide a flask constructed for banking procedures and which permits an unusual area of plunger surface to be applied to the dental material in forcing it into the above mentioned space.

Still another object of this invention is to provide a dental flask wherein the case may be removed therefrom with little danger of breaking or otherwise damaging the teeth or denture.

Other objects of my invention will be apparent from the following description, it being understood that the above general statements of the objects of my invention are intended to describe and not limit it in any manner.

Referring to the drawings:

Fig. 1 is a top plan view of the bottom section of the improved flask.

Fig. 2 is a similar view of the intermediate section.

Fig. 3 is a similar view of the top section.

Fig. 4 is a composite view, partly broken away, of the three sections but separated to illustrate their assembly.

Fig. 5- is a perspective view of the top section with the plunger formed therein.

Fig. 6 is a perspective view of the intermediate section including the waxed up case.

Fig. '7 is a perspective view of the bottom section including the investment.

The flask comprises the bottom section or portion It which is in the form of a cup-shaped receptacle having a front wall II, a rear wall l2, a floor l3 and a knock-out plug I4. Ears l5 and it are formed integrally with respective side walls I1 and 18. The ears are provided with openings l9 and 28 so that bolts may be inserted therein as hereinafter described.

The intermediate section 29 is formed with ears 30 and 3! having openings 32 and 33 which mate. with the openings l9 and 20. Section 29 is substantially U-shaped and is formed with a ceiling. 34. It is further formed with a pair of depending pins'35 and 35 which are'adapted to be received in openings 2| and 22 of the bottom section Ill. Upstanding pins 31 and 38 are formed on the forepart of intermediate section 29.

The top section 4!! is U-shaped with the central portion thereof taking the form of a depression 4i which is palate-shaped. Such depression 4! extends from the top front portion of section 49 and transversely downwardly to the lower rear section thereof as illustrated in Fig. 4. The function of such depression 4| is to effect a more uniform curing of the thermoplastic material when the asembled flask is processed by heat for this purpose. As was set forth in my prior patent application Serial No. 726,864, filed February 6, 1947, now Patent No. 2,527,647, such construction has the effect of producing a denture substantially free of structural irregularities and variations of density which are attributable to defects in the curing operation.

Top section 40 is formed with openings 42 and 43 which receive the pins 37 and 38 so as to effect such assembly of the flask as is suitable for insertion in a press in curing the denture. Section 45 is further formed with a depending flange member 44 which encloses the rear end of the flask and thus covers the open rear of the intermediate section 29.

In order to utilize the dental flask of the instant application, the model and the waxed up case including the artificial teeth are first invested in the bottom section I0. A separating medium such as oil is applied to the investment. Thereafter the intermediate section 29 is applied thereover and these two sections together become what may be referred to as the lower part of the flask. Plaster 45 is then poured into the intermediate section and shaped to form a substantially planar surface. This is allowed to set. v

The exposed surfaces of the plaster are then coated with oil or other separating medium. Then the central hollow is filled with plaster whereupon the top or cover section 40 is placed in position and allowed to set. Cover section 40 is approximately to inch deep so that the centrally applied plaster fills the hollow thereof.

The assembled flask with the invested model therein is then boiled for about minutes as in the usual method of removing the wax. At this time, both top section-40 and center section 29 are removed whereupon it will be found that the teeth 46 are retained in the intermediate section 29. Such teeth are accessible from practically any desired angle so that they and the cast may be cleaned and prepared prior to packing. It will be appreciated, therefore, that by the provision of the central or intermediate section, unusually desirable access is afforded to the teeth and cast prior to application of the denture material.

After the last operation, the bottom section In and the intermediate section 29 are locked together as by employing bolts 56 and nuts 51 on the respective ears of the sections. These are tightened so as to effect a firm and positive connection between the intermediate and bottom sections. At this time, the space left by the removed wax is packed with acrylic plastic or any other suitable material. The rear opening of intermediate section 29 is effective in permitting this operation to be accomplished with facility and accuracy inasmuch as such space is visually and physically accessible from the entire lingual and palatal portion. This operation having been completed, the top section 29 is placed in position, the plaster 52 taking the form of a mound which is utilized to force the applied material into the denture space. It will be noted that such mound 52 is the plaster which was centrally applied to the oil-coated areas of section 29. The assembled flask is then subjected to pressure in a bench press whereupon the mound 52 forces the plastic denture material into the denture space. The degree of compression could be very great, if desired, without fracturing the plaster investment since such investment is protected throughout by surrounding metallic walls of considerable sturdiness.

After the initial compression action, the top section 40 may be removed and further plastic denture material may be added, if required. It is generally agreed that there is a sizeable loss of material during the curing process. Therefore, it is necessary to have a suflicient quantity of surplus material in the denture cavity to start with. This surplus material will in no Way interfere with the planned occlusion of the teeth.

The cover is re-applied and the flask is closed in the bench press until there is at least 2 mm. space between the cover and body of the flask while under pressure. The assembled flask is thereafter placed in the conventional compensating spring press, the assembly then being subjected to the usual processing procedure. During the processing, the spring press will exert pressure on the flask and thereby feed the excess material into the denture cavity, assuring a more dense and better fitting denture. The spring press is then taken off and the finished denture is removed as described above.

The depending wall or flange 44 is of particular utility in that it backs up the mound which is formed on the upper section 40 and enhances its retention thereon in cooperation with the hollow nature of such section 40.

The ceiling 34 of the central or intermediate section 29 is of importance in protecting the top of the plaster investment while the plunger force is applied. Such investment cannot break away because of such central ceiling. The two-piece nature of the lower portion of the flask is likewise of considerable importance in not only permitting the operator to work directly on the teeth and cast by separating the lower half as above described, but it permits the case to be knocked out with safety and convenience. It will be understood that the ceiling 34 would ordinarily be a hindrance to such knocking out of the case but since the lower portion of the flask may be separated in two parts, such knocking out is facilitated.

In removing the finished denture from the lower portion of the flask, the plug I4 may be forced inwardly in the usual manner as by being threaded on the floor of section [0 and turned inwardly with a screw driver. This forces the investment out of such bottom section so that it is retained by the intermediate section. Knockout plug 55 may then be struck, as by a hammer, so as to remove the case laterally from the intermediate section. Such an arrangement facilitates the removal of the investment in that no undercuts are encountered which might retain a portion thereof. Thus, the action of plug 55 is to knock out the complete investment.

What is claimed is:

1. A dental flask comprising a bottom section, an intermediate section, and a top section, said intermediate section being U-shaped and including a U-shaped ceiling formed thereon, said top section resting on said ceiling'and being formed with a rear depending flange for covering the open side of said U-shaped intermediate section so as to form the completed flask.

2. A dental flask according to claim 1 and including locking ears formed on the bottom and intermediate sections respectively and locking bolts therefor whereby said bottom and. intermediate sections may be locked together.

3. A dental flask according to claim 2 and wherein said top section is formed with a palateshaped depression centrally thereof, said depression extending transversely downwardly from the top front portion of the top section to the lower rear portion thereof.

4. A dental flask comprising a bottom section,

an intermediate section and a top section, said bottom section having a floor and said intermediate section being U-shaped, a first knock-out plug on the floor of said bottom section and a second knock-out plug on said intermediate section on a side opposite the opening of the U thereof.

5. A dental flask comprising a bottom section, an intermediate section and a top section, said bottom section having a floor and said intermediate section being u-shaped, a first knock-out plug on the floor of said bottom section and a second knock-out plug on said intermediate section on a side opposite the opening of the U thereof, locking ears on said bottom and intermediate sections respectively whereby said two sections may be locked together to form a lower model investing portion of the flask, said intermediate section being formed with a U-shaped ceiling serving as a top enclosure for said model investing portion, said top section being formed with a rear depending flange for covering the open side of said U-shaped intermediate section so as to complete the assembly of the flask.

6. A dental flask according to claim 5 and including a palate-shaped depression formed on said top section, said depression extending from the top front portion of said section downwardly to the lower rear portion thereof, said top section substantially resting on the ceiling of said intermediate section, upstanding pins on said ceiling, said top section being formed with openings for receiving said pins.

NATHAN OPOTOW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 283,928 Seaoury Aug. 28, 1883 285,243 Elliot Sept. 18, 1883 544,095 Griswold Aug. 6, 1895 620,303 Groshans Feb. 28, 1899 1,949,227 Wiechert Feb. 27, 1934 FOREIGN PATENTS Number Country Date 444,533 Germany May 24, 1927 

